No analytical technique currently allows to directly characterize a petroleum product having a wide boiling range. Fractional distillation is necessary in order to apply to each fraction standard analytical methods or methods described in the literature. This procedure is very long and expensive, and it can lead to errors.
Considerable work and many publications deal with GC simulated distillation, GC-GC and GC-LC couplings and associated characterization methods. Examples thereof are:
Simulated distillation: PA1 Couplings:
ASTM D 5307--1992; &lt;&lt;Determination of Boiling Range Distribution of Crude Petroleum by Gas Chromatography&gt;&gt;, American Society for Testing and Materials; PA0 J. P. Durand, et al : &lt;&lt;Simulated Distillation Methods for Petroleum Fractions with Minimal Residue in the Boiling range of 35-700.degree. C.&gt;&gt;, J. of Chromatographic Science, Vol.36, September 1998. PA0 ASTM D 5134--1990, &lt;&lt;Detailed Analysis of Petroleum Naphthas Through n-Nonane by Capillary Gas Chromatography&gt;&gt;, American Society for Testing and Materials; PA0 NF07-086, &lt;&lt;Determination des teneurs en families chimiques d'hydrocarbures dans les essences pour moteurs automobiles a partir de l'analyse detaillee&gt;&gt;, Association Fran.cedilla.aise de normalisation, Paris La Defense, Cedex. PA0 J. P. Durand et al: &lt;&lt;Direct and Automatic Capillary GC Analysis for Molecular Weight Determination and Distribution, in Crude Oils and Condensates up to C20&gt;&gt;, J. High Resolut. Chromatogr., 12, 1989, 230-234; PA0 J. P. Durand et al: &lt;&lt;Detailed Characterization of Petroleum Products with Capillary GC analyzers&gt;&gt;, Analysis, 1995, 23, 481-483. PA0 G. W. Kelly et al: &lt;&lt;The use of combined LC-GC for the analysis of fuel products: a review&gt;&gt;, JHRC, Vol.17, 1994, 390-397; PA0 A. Trisciani et al: &lt;&lt;Characterization of fuel samples by on-line LC-GC with automatic group-type separation of hydrocarbons&gt;&gt;, JHRC, Vol.17, 1994, 452-456; PA0 K. J. Welch et al: &lt;&lt;Analysis of fossil fuel fractions by on-line coupled microcolumn HPLC-capillary GC-MS&gt;&gt;, HRC, 15, 1992, 171-175; PA0 C. Ostman et al: &lt;&lt;On-line liquid chromatography-gas chromatography for automated clean-up and analysis of polycyclic aromatic hydrocarbons&gt;&gt;, HRC, 15, 1992, 437-443. PA0 a first gas chromatography device laid-out to perform separation of the sample into at least a first light fraction and at least another, heavier fraction, PA0 retention means for collecting said fractions after separation, PA0 one or more gas chromatography columns for detailed analysis of each light fraction, by connecting up the corresponding retention means, and PA0 a combined liquid and gas chromatography unit for analysing each one of the heavier fractions by connecting up and flushing of the corresponding retention means.
There are standard detailed analysis methods for the light fraction.
The use of GC-GC coupling only for analysis of the light fraction without distillation of the sample with these methods is also described by:
There are also many publications on LC-GC coupling. The interfaces allowing on-line coupling between LC and GC are described by K. Grob in &lt;&lt;On-line coupled LC-GC&gt;&gt;, Huthig Ed., 1991.
As for characterization of middle and heavy fractions, the following examples can be cited: